The referenced sheet rock support of Molloy disclosed and claimed in U.S. Pat. No. 4,733,844 has proven to be highly serviceable and readily adaptable and adjustable to varied working areas, heights and loads and in providing ease of maneuverability. That prior sheetrock support device is easily adjusted to various desired heights and to the desired upward pressures in one step and also is easily released from its temporary supporting position below the sheetrock after such a ceiling panel has been permanently fastened in place on the overhead structure. The present invention provides a number of improvements over that prior successful sheetrock support device.
In U.S. Pat. No. 4,695,028 of Hunter is disclosed a device for holding construction materials, such as sheet rock, up against an overhead ceiling structure. A long tension spring is located within an outer lower tubular column and is attached at its upper end to the upper end of this tubular column. The lower end of this tension spring is attached to the lower end of an upper shaft which telescopes within the outer lower tube. Thus, this tension spring is continually urging the upper shaft toward the ceiling. In operation, the user must grasp an arm of a sheet rock support located at the top end of the telescoping upper shaft and then pull down on this arm whenever the user wishes to move the sheet rock support structure downwardly away from the ceiling. In other words, the user is forced to fight against this long tension spring whenever the user wants to reduce the height of the sheet rock support structure by telescoping the upper shaft downwardly within the tubular column. The further down that the user telescopes the upper shaft, the greater the opposing force of the stretched tension spring which must be overcome.
A first problem with this Hunter sheetrock support device is that the user is always fighting against a powerful and long tension spring when reducing height. This tension spring must be long, with a long available travel and be powerful to be able to accommodate various floor-to-ceiling heights always with enough residual force available at maximum height in order to support the sheetrock load. Consequently, a second problem with the Hunter device occurs when supporting sheetrock against a low ceiling in that the upward thrust of the stretched tension spring may excessively compress the sheetrock against the ceiling joists or other building structure.
After the user has pulled down on the overhead support arms for fully telescoping the upper shaft, a trigger handle having a second spring serving as a trigger spring, engages in an aperture in the upper shaft. The trigger handle is now holding the upper shaft in fully telescoped relationship and the long tension spring is now fully stretched. A third problem with the Hunter device is the inherent danger resulting from the stored energy in a large, long stretched tension spring temporarily held in its fully stretched condition by a trigger handle. In effect, it is like a catapult. Inadvertent release of the trigger handle when no sheetrock has yet been loaded onto the support, could cause the support to accelerate upwardly and slam against the ceiling with considerable speed, momentum and impact force. If a person inadvertently happened to have a hand, arm or head in the path of such a catapult-like action, severe injury could occur.
Further problems with such a prior art device result from the awkwardness and unbalanced offset weight of a laterally projecting trigger handle. In addition, there is the extra cost involved with the Hunter trigger handle, its hinged mounting and its relatively large compression trigger spring. The X-shaped sheetrock support at the top is bulky, heavy, and difficult to move around.
It is an object of the present invention to provide a ceiling panel installation support (which may be called a "sheetrock jack") that is truly convenient to use, relatively light in weight, compact for travel from job to job and for storage, and relatively inexpensive and not complex.